Reference may be made to the following U.S. Patents of interest: U.S. Pat. Nos. 1,845,568; 3,113,516; 3,203,832; 3,290,060; 3,410,711; 4,045,053; 4,403,793.
Credit card transaction slips are in common use for commercial transactions. Normally, two or more transaction slips are bound together at one end with a duplicating medium slip or duplicating carbon slip to form a pack or form set. The transaction slips have particular locations and blocks of locations printed on the slip for recording information related to the commercial transaction.
Typically, the customer's credit card with information in raised sections is placed in an imprinting fixture. The transaction slip pack is placed on top of the credit card and a roller is rolled over the pack and credt card. Information on the raised section of the credit card is thus transferred by imprinting the duplicating medium onto the lower face, i.e., the back or reverse side, of the top transaction slip as well as onto the upper face, i.e., the front side, of the bottom transaction slip. The imprinted information may consist of the credit card customer's name, expiration date, and account number, the name, address and account number of the merchant (found on the merchant plate/card attached on the imprinter fixture), and the transaction dollar amount.
Thus, during imprinting, the raised numbers and letters on the customer's credit card and the merchant's plate are transferred for the duplicating medium slip, such as a carbon paper, to the lower face (back) of the top transaction slip and to the upper face (front) of the bottom transaction slip. Since the imprinted carbon numbers and letters on the lower face of the top transaction slip must be read through the top slip from the upper face, it is required that the imprinting be legible when viewed through the paper.
Paper mills manufacture the paper to be used for the top transaction slips on a paper machine using special pulps and other special machinery and processes to make the paper more nearly transparent and at least as transparent as possible. Other paper mills who do not use special pulps or have such special machinery treat translucent paper with chemical solutions or chemical coatings which impregnate the paper to make the paper as near transparent as possible. The terms "transparent", "translucent" and "opaque" as used herein are defined as follows: "transparent" means having the property of transmitting light without appreciable scattering or diffusion so that bodies lying beyond are entirely visible; "translucent" means having the property of admitting and diffusing light so that objects beyond cannot be clearly distinguished; and "opaque" means having the property of blocking light to the extent that objects beyond cannot be distinguished.
In both of the aforementioned prior art techniques, paper manufacturers or others attempt to make the paper as transparent as possible in order that the carbon imprint on the lower face of the paper can be a visible and legible as possible when viewed from the top face and through the paper. Thus, in the prior art, an initial translucent paper, i.e., a paper which admits and diffuses light so that objects beyond cannot be clearly distinguished, is treated to make the paper more nearly transparent so that objects beyond the paper can become more nearly visible and legible when viewed through the paper.
Despite such prior expensive efforts, sometimes the imprinting on the top transaction slip is not as visible and legible as desired. Also, the prior art attempts to make a more transparent top transaction slip require expensive, high quality paper and pulp or costly paper treating solutions and processes. Furthermore, even using such special pulps and special processes, there is sometimes produced a less nearly transparent paper, due to pulp quality, coating quality, etc. Prior art attempts to obtain legible imprinting are thus expensive, unreliable and do not consistently produce the previously desired more nearly transparent paper.
It is therefore desired to equal or improve the visibility and legibility of the lower face imprinting when viewed through the top transaction slip with the least expense as possible so that another grade, less expensive paper may be used with treating processes that are not as costly and which may be accomplished on a press and during the printing/manufacturing operation for a credit card from set or pack.